When you want to change the server time source or you get error eventID 12, just type at command prompt as Administrator:
w32tm /config /manualpeerlist:server,0x8, /syncfromflags:manual /update
where server is the name of the time source that you want to configure, and then press ENTER.
Restart the Windows Time service
net stop w32time & net start w32time
Resynchronize the Windows Time service client with the time source peer.
To Check configuration :
w32tm /query /configuration w32tm /query /status Time /T
Microsoft has issued hotfix that is a wizard which set the time server automatically according to your NTP server preferences (Like: time.windows.com)
you can download is it here
To set time service on server manually you can follow this link to Microsoft :